Nonlinear photonic crystal fibres: pushing the zero-dispersion towards the visible

The strong waveguide dispersion in photonic crystal fibres (PCFs) provides unique opportunities for nonlinear optics with a zero-dispersion wavelength lambda(0) far below the limit of similar to 1.3 mu m set by the material dispersion of silica. By tuning the air hole diameter d, the pitch Lambda, and the number of rings of air holes N, the strong waveguide dispersion can in principle be used to extend lambda(0) well into the visible, albeit to some extent at the cost of multi-mode operation. We study in detail the interplay of the zero-dispersion wavelength, the cutoff wavelength lambda(c), and the leakage loss in the parameter space spanned by d, Lambda, and N. As a particular result, we identify values of d (similar to 500 nm) and Lambda (similar to 700 nm) which facilitate the shortest possible zero-dispersion wavelength (similar to 700 nm), while the fibre is still in single-mode for longer wavelengths.